亚洲夏季风区大气能量谱分析

用1979年FGGE—Ⅲb资料,对亚洲及其邻域的总能量、大气显热源和水汽汇进行谱分析.结果表明:准40天振荡是亚洲夏季风区的主要特征振荡.振荡方差贡献的分布以及振荡源中心位置反映出在印度、孟加拉湾、南海和东亚大陆上空夏季风系统具有一定的独立性。长江以北地区主要受中纬度系统影响,华南沿海和云贵地区则分别受南海和孟加拉湾地区夏季风系统的影响.振荡从主要振荡源向外传播,东亚季风区振荡主要从东南向西北传播.总能量和水汽汇振荡的传播还表明,从南半球有明显的向北传播通道.这些通道与越赤道气流通道大致相对应.大气显热源的振荡则无此特征,但它对大气环流准定常状态的维持有一定的影响,孟加拉湾湾头和南海既是热源中心,亦为准双周振荡的源区.

A Spectrum Analysis of the Atmospheric Energy Over the Asian Summer Monsoon Areas

Using the FGGE-III(b) data of 1979, this paper analyzed the spectrum structure of the total energy, the apparent heat source and the moisture sink over the Asian summer monsoon areas. The spectrum distribution for different periods and the propagation of oscillations are investigated. It is found that these distribution and propagation have their synoptic and climatologic meaning, when they are compared with the summer monsoon circulation. The results also show that the quasi-40 days oscillation is the most significant one in these areas. The distribution of spectrum variance and the propagation pattern indicate the independence of the monsoon systems over India, the Bay of Bengal, the South China Sea and the continental East Asia. Different monsoon systems are dominant in different areas, respectively. For instance, the midlatitude system is dominant in north China north of the Yangtze River, the coastal area in south China is controlled by the monsoon of the South China Sea, and the southwest China, such as Yunnan, is mainly inflerenced by the monsoon of the Bay of Bengal. Near the equator, there are some passages for propagating oscillations of the total energy and moisture, which are consistent with those for the northward cross-equatorial flows. However, such a feature does not belong to the oscillation of apparent heat source of the atmosphere, which makes its contribution mainly to the quasi-stable state of the atmospheric general circulation.